The invention relates to an improvement to brew chambers used to hold ground coffee beans within a filter paper ready to receive hot brewing water for brewing coffee and draining it to a decanter.
The invention is particularly directed to both automatic and pour over coffee devices wherein a brew chamber is supported by an upper housing of the coffeemaker directly below the outlet of a siphon tube that conveys hot water from a heated tank within the device. These siphon-type coffeemakers are found both in homes and public restaurants.
Usually, the brew chamber has a frusto-conical shape having an open top with a rim around the upper edge. The rim serves to slide within a pair of opposing guide slots on the coffeemaker housing for holding the chamber. The brew chamber will also usually have a sump in the bottom wall with an outlet orifice, through which the brewed coffee drains into a decanter below.
At one side of the brew chamber there is typically a handle grip for maneuvering the brew chamber. When a batch of coffee is desired the handle may be grasped and the brew chamber slid outwardly of the guide slots away from the device. Thereafter, a complementarily-shaped filter paper is placed into the brew chamber and the appropriate amount of a blend of ground coffee beans is placed onto the filter paper. Then, the brew chamber is returned below the siphon opening of the coffeemaker by sliding the edge rim into the opposing channels or slots for supporting the brew chamber.
So that during brewing the coffee grounds do not clog the outlet orifice and cause the brewing coffee to overflow, it has been found to be necessary to support the filter paper above the bottom wall of the brew chamber so that a constant even flow is created for the brewed coffee leaving the coffee grounds. It has been found important to provide means for spacing the filter paper at a certain spacing above the bottom of the brew chamber so that a smooth flow of brewed coffee occurs below the filter paper to drain outwardly from the outlet orifice of the brew chamber.
In the past, the use of plastics for making brew chambers has become quite common. Since plastics are easy to mold into an infinite number of shapes, the spacing means for the filter paper has been provided by integrally molding with the brew chamber upwardly extending support ribs, tabs, and the like, capable of supporting the underside of the filter paper and spacingit away from the outlet orifice and bottom wall of the brew chamber. These molded supports satisfy the free flow drainage requirement and prevent clogging. One plastic quite commonly used to make brew chambers is polypropylene due to its heat resistance, durability and strength.
However, problems with plastic brew chambers have been encountered. One particular concern is the cleaning of the brew chamber once it has become stained with coffee. If plastic, such as polypropylene, is not cleaned on almost a daily basis in a restaurant, a dark staining may occur with the additional possibility of causing bad tasting coffee from residue left on the sidewall of the brew chamber. These problems are especially undesirable for restaurant coffeemakers, which establishments usually seek to serve good tasting coffee and also meet local health codes and other sanitary requirements.
An additional problem with plastic brew chambers is heat deformation that can be caused at the outlet orifice should someone inadvertently place the brew chamber on a warming plate for the decanter, or other hot surface. Sometimes, brew chambers are provided with downwardly molded legs which conveniently support the brew chamber in a level position when it is to be filled with a filter paper and fresh ground coffee. Legs are usually required because the bottom wall of the brew chamber is most often constructed to taper toward a sump and without legs the brew chamber would not be capable of resting in a level manner. The provision of legs can help somewhat to sapce the outlet orifice from a hot supporting surface below. The outlet orifice design for the brew chambers in the prior art alomost universally includes a downward projecting circumferential lip which assures that the outward flow of the brewed coffee is in a controlled steady stream rather than latching and randomly channeling on the bottom of the brew chamber adjacent the orifice. The design of a brew chamber preferably permits the outlet orifice to be as close as possible to the opening of the receiving decanter therebelow. Thus, even though support feet may be provided to allow the brew chamber to be poised upright and level on a surface for filling, the outlet orifice and depending lip are usually insubstantially the same plane of the bottom of the legs. Therefore, even though legs may be provided, the problem of heat deformation by placement on a hot plate or stove can still occur since the orifice would usually be close to the supporting surface for the legs.
Of course, unwanted deformation to integrally molded plastic base support legs themselves can also occur if the brew chamber is accidently placed on a hot surface.
The function of the lip depending around an outlet orifice is to create a nozzle-effect which is critical to an even flow rate of coffee. The outlet orifice is designed to have a certain diameter and a lip size that are calculated with respect to the size and shape of the brew chamber. Thus, if there is heat deformation changing the shape of the orifice, the outward flow may be restricted or altered so that the brewing coffee may clog the drain, become overextracted, or perhaps be underextracted by flowing too quickly from the brew chamber. Since many restaurants take great pride in the quality of coffee that they serve, the preservation of the intended designs of the orifice outlet and nozzle-like lip are critical to this end.
In further preventing the clogging of the outlet orifice, pleated filter papers are quite commonly provided which have sideward pleats on a tapered sidewall of the filter paper, which serve to space the filter paper from the complementarly sloped sidewall of the brew chamber. The bottom of standard filter paper is smooth and flat. The bottom is also generally circular having a diameter usually of about 4 to 6 inches for restaurant coffeemakers. The polypropylene brew chambers have require sometimes up to about 12 radial support ridges to surely support the bottom of this standard sized filter paper while holding fresh ground coffee that becomes heavily saturated with hot brewing water in order to prevent the paper from sagging downwardly to clog the outlet orifice. Accordingly, to achieve an effective spacing of the filter paper, the support ribs or flanges, must evenly and surely support the bottom surface of the filter paper without impeding an even flow of the brewing coffee passing through the filter paper to the outlet orifice.
It would be advantageous to make a brew chamber of stainless steel to take advantage of its excellent stain resistant properties and avoid the lingering bad taste and odor problems of plastic. A hurdle to the use of stainless steel is with providing a spacer means, also made of stainless steel, which spaces the filter paper from the bottom wall. The metal forming processes for related shapes made of stainless steel involve stamping techniques known to the metal working arts. The stamping procedure does not allow for forming integral spacer supports at the bottom of a stainless steel brew chamber unlike in the forming of thin flanges and other ridges for molded plastics. Since an effective spacer canot be integrally formed of stainless steel, a separate member is required. As a result, there are inherent problems in seeking to use stainless steel for providing a spacer support means that will fit within the brew chamber at an appropriate spacing and effectively function as a filter paper support to allow for a desired even flow from a stainless steel brew chamber.
By providing a separate spacer support member it is also a concern that after a batch of coffee is brewed, and the used grounds must be dispensed, a separate spacer element would not be accidentally thrown away into the refuse bin as the grounds are dumped. It is therefore an allied requirement to find a separate stainless steel filter support for spacing the filter paper from the bottom of the stainless steel brew chamber which is securely but removably attachable to the brew chamber so that firstly, the brew chamber may be emptied of its used load of coffee grounds and filter paper, and secondly, able to be removed for the cleaning of the support as well as the entire inner surface of the brew chamber.
A satisfactory stainless steel brew chamber and removable frame insert would also incorporate stainless steel foot supports at the outside bottom of the brew chamber whereby the brew chamber may stand level on a surface while a new filter paper is inserted and subsequent load of fresh coffee grounds deposited into it. The foot supports would also be required to support the lip of the outlet orifice sufficiently above the countertop, or table, on which the brew chamber would be placed in order to prevent bumping the lip and deforming the orifice shape and design. With stainless steel the problem of plastic heat deformation is eliminated.
The prsent invention solves all the foregoing problems and needs of the industry by eliminating the use of a plastic brew chamber by providing a stainless steel brew chamber and filter space support frame in satisfaction of those needs, as will be explained below.